I found a compaq s720 monitor on the side of the road with the vga cable cut. I was going to try and rewire it today but there's one wire that goes into the motherboard that said plug underneath. Any idea what this means? Thanks. The cut cable has 10 wires if that helps.
https://imgur.com/gallery/FryHa8U
Crt monitor with cut vga cable
Re: Crt monitor with cut vga cable
It might just be ground. You should be able to figure that out pretty easily by using a multimeter in continuity mode and seeing which pins have continuity to ground.
If it's not ground, it's going to be either the monitor ID optional pin (11) or the 5V pin (9).
This is assuming you have all the other pins correctly routed. I can see on the PCB that it clearly labels SDA and SCL, so you should have your DCC pins, and the H sync and V sync are labeled. The colors should be super obvious because the cut ends of the wires inside the shielding will be color coded with the color wires having a matching color ground wire for each. There will also be a bunch of other grounds. I don't think which ground goes to which ground is terribly important as the purpose is to prevent noise from being introduced to the signal
but my money is one of the grounds, it might just be the cable shielding ground if it says something like that
Also, sometimes people cut cables off of electronics as a warning to not plug it in because it's broken and potentially dangerous. Not always, but it's something people (especially older people) do
If it's not ground, it's going to be either the monitor ID optional pin (11) or the 5V pin (9).
This is assuming you have all the other pins correctly routed. I can see on the PCB that it clearly labels SDA and SCL, so you should have your DCC pins, and the H sync and V sync are labeled. The colors should be super obvious because the cut ends of the wires inside the shielding will be color coded with the color wires having a matching color ground wire for each. There will also be a bunch of other grounds. I don't think which ground goes to which ground is terribly important as the purpose is to prevent noise from being introduced to the signal
but my money is one of the grounds, it might just be the cable shielding ground if it says something like that
Also, sometimes people cut cables off of electronics as a warning to not plug it in because it's broken and potentially dangerous. Not always, but it's something people (especially older people) do
Re: Crt monitor with cut vga cable
Every time I see a CRT on the side of the road it has a cut cable. I always assumed it was scrappers desperate for copper wire.
Re: Crt monitor with cut vga cable
I guess the copper is valuable, but why bother just taking the cord when e-cycle places will take the whole thing and process out the gold? I know of a couple places in the DC area that do that and they make a lot of money off of it. I don't suppose you'd get a lot from them for it in scrap, but it's more than the nothing you'd get for it on the side of the road
-
maxtherabbit
- Posts: 1763
- Joined: Mon Mar 05, 2018 4:03 pm
Re: Crt monitor with cut vga cable
scrap yards around here will not take monitors or tvs
Re: Crt monitor with cut vga cable
The amount of copper you'd get from a VGA cord is inconsequential. First, due to the tiny guage of it, it'd be #2 grade, second, having to strip wires just a few times larger than a human hair is not profitable, third, even if you strip it all, you are looking at a couple grams of copper at best, lol.
In short, its nothing to do with scrap metal. More likely, as dumb as it sounds, it was done by some ignorant business to prevent potential "data theft".
Seriously.
In short, its nothing to do with scrap metal. More likely, as dumb as it sounds, it was done by some ignorant business to prevent potential "data theft".
Seriously.Re: Crt monitor with cut vga cable
The monitor was probably stolen from the closed school next street over. It has a department of education sticker on it. I manage to rewire the vga core but I got no white color.
https://imgur.com/gallery/ApTdMbk
https://imgur.com/gallery/VlDGdCA
https://imgur.com/gallery/ApTdMbk
https://imgur.com/gallery/VlDGdCA
Re: Crt monitor with cut vga cable
Thats really strange as white is R, G, B at 255. Im trying to think what in the signal chain would cause all colors to work, yet not give white. Very odd. You should be able to use the 240p suite to step-mix all colors to create a white, no? What happens if you do Red 255 + Blue 255? Do you get magenta? If you do, try adding green a bit and see what happens. White is not its own signal on an analog CRT. You might want to post on r/CRTgaming on reddit to see if anyone there has a clue. I cant think of anything right off the top of my head that would cause that.
Bonus: Came across a really innovative CRT display that Ive never seen in googling what could cause your issue.
https://hackaday.com/2019/01/17/sharpes ... s-a-trick/
Bonus: Came across a really innovative CRT display that Ive never seen in googling what could cause your issue.
https://hackaday.com/2019/01/17/sharpes ... s-a-trick/
Re: Crt monitor with cut vga cable
Not scrapyards. E-waste places are big mills that just take old PCBs and broken stuff and throw it in a big processing vat to extract the gold. They take and break down pretty much anything and get bricks of gold out volume
There are two I know of in the DC area, one was opened by a guy I worked with at UMD in the machine shop, and he's doing quite well off with it.
Might be caused by A) that particular part of the CRT at the bottom is fubar B) maybe something with the power supply is messed up and it can't produce voltage high enough to display big areas of white C) idk about this one, but perhaps there's something weird with the cut-offs VS the drive circuitry
no matter the case, I would expect this one is a lost cause. I also can't think of a wiring reason he would be getting RGB and not white, doesn't make sense
That's cool. There's some other weird color tech out there like the Beam Index and the Sony ChromatronBonus: Came across a really innovative CRT display that Ive never seen in googling what could cause your issue.
https://hackaday.com/2019/01/17/sharpes ... s-a-trick/
All super neat stuff
Re: Crt monitor with cut vga cable
Man, I would keep that thing just to tinker! Thats a really weird problem. Did you try adjusting the drive pots? Try bringing them down maybe? They dont look like they all start to get "white" on the right side on the color bars you posted. If it was a power supply being drawn down, the other colors should show issue as well. Maybe contact ol Retrotech on Twitter and bounce it off of him, maybe hes seen something like that?
Can you try creating full screen white by gradually mixing colors in the 240p suite?
Also-- I just thought of this-- this model has an OSD that should have white text or graphics in it-- pull it up and see if there is any white in the OSD. If there is, the problem is almost certainly in your cable or your source.
Re: Crt monitor with cut vga cable
I check the osd on the monitor and there is white on the screen. So I decided to hook my og xbox with my gbs control and plug it into the monitor and it works. So it must be my cable for the dreamcast.
https://imgur.com/gallery/Se8rHCW
https://imgur.com/gallery/Se8rHCW
Re: Crt monitor with cut vga cable
Aha!! Called it! Saved another one, excellent!rejhogan wrote: ↑Wed Feb 07, 2024 2:04 pm I check the osd on the monitor and there is white on the screen. So I decided to hook my og xbox with my gbs control and plug it into the monitor and it works. So it must be my cable for the dreamcast.
https://imgur.com/gallery/Se8rHCW
Re: Crt monitor with cut vga cable
Im so glad it the cable and not the mointor lol. I felt so dumb after cheching it. Thanks everyone for taking your time to reply and help.
Re: Crt monitor with cut vga cable
Awesome. Looks pretty good too!
Might benefit from some color management though. Maybe get some 240p Test Suite and go through the white balance procedure with HFCR